Buy the Prazipro which is your first link. You probably should treat 2-3 times about 7-10 days apart. One ounce treats 120 gallons, so you will need to buy 3 ounces to be on the safe side. The good news is Prazipro is about as safe as any medication which you can put in your display tank.
I haven't read through the black ick posts, but there were always a few spots on my YTang and Moorish Idol. I treated the tank with Prazipro for flukes 2 weeks ago and all the black spots went away. Black ick is actually a type of Turbellaria worm and it must be susceptable to prazipro which will kill certain worms.